1. Field of the Invention
The present invention relates to a method of reading individual information of a detachable unit, an individual information reading device, an apparatus having the individual information reading device, and a detachable unit, and more particularly to reading individual information of a detachable unit in an image forming apparatus such as a printer, copier or facsimile having a developer for developing a latent image on a latent image carrier and a toner storage for supplying internally stored toner to the developer.
2. Description of the Related Art
The technical field covered by the present invention is not limited to an image forming apparatus such as a printer, copier or facsimile. However, the related art will now be described using the example of an image forming apparatus such as a printer, copier or facsimile provided with a developer for developing a latent image on a latent image carrier and a toner storage for supplying internally stored toner to the developer.
With the above conventional image forming apparatus, a one-component developing method and a two-component developing method are known as methods of developing a latent image carried on a latent image carrier such as a photosensitive member. The one-component developing method involves developing the latent image using a one-component developing material consisting primarily of toner. In contrast, the two-component developing method involves developing the latent image using a two-component developing material containing toner and a magnetic carrier.
Since the stocked amount of toner is limited in both methods, new toner needs to be set in the image forming apparatus as necessary. As for the method of setting new toner, a method is known in which a toner contained type developer filled with toner is replaced at the point at which the toner runs out. A method is also known in which new toner is supplemented directly to the image forming apparatus or together with a toner storage unit. The latter method is advantageous in terms of running costs.
An image forming apparatus in which new toner is set therein using the latter method is disclosed in Japanese Patent Laid-Open No. 2000-3116. The image forming apparatus comprises a toner storage (hopper) that stores toner for supplying to the developer, remaining toner remaining amount calculation means that calculates the amount of toner remaining in the toner storage, and display means that displays the calculated amount of remaining toner. The remaining toner remaining amount calculation means calculates the amount of remaining toner in the toner storage based on the accumulated number of rotations of a motor constituting a driving source of a movable member disposed in the toner storage, and displays the calculated amount of remaining toner on the display means. The user is able to judge whether toner setting is required in relation to the image forming apparatus based on this display, and set new toner in the toner storage as necessary. However, a large toner storage capable of stocking a large amount of toner is required in order to avoid a situation where the user is forced to perform toner setting frequently.
In order to control the change in state resulting from toner setting, information required in image forming or information indicating new or used may be provided on a detachable unit such as a toner bottle or a toner cartridge. Methods using thermosensible paper typified by Japanese Patent Laid-Open No. 07-036348 and memory methods typified by Japanese Patent Laid-Open No. 2004-309945 are exemplary means of realizing the above. Methods using simple barcodes typified by Japanese Patent Laid-Open No. 08-039824 have has also be proposed.
However, a method that uses thermosensible paper such as Japanese Patent Laid-Open No. 07-036348 unavoidably requires electrical contacts. The presence of these electrical contacts, which are a contributing factor in contact failure and the like, decreases the reliability of the apparatus.
While a contactless memory method such as Japanese Patent Laid-Open No. 2004-309945 is superior in terms of reliability, the configuration is complex and costly, and the placement of conductors such as metal is restricted given the use of radio waves.
Consequently, a method such as Japanese Patent Laid-Open No. 08-039824 that involves appended a barcode to a detachable unit is used in order to realize a simple configuration cost effectively. However, when a simple barcode method is used with a detachable unit as in Japanese Patent Laid-Open No. 08-039824, the barcode data cannot be stably detected.
For example, the following problem occurs when reading a barcode from a rotating toner bottle. That is, a brush motor is generally used to rotate the toner storage unit. Since the torque required for rotation varies depending on the amount of remaining toner in the toner storage unit, a brush motor is employed as a motor tolerant of such variation. While this brush motor has a large torque and is effective against load fluctuation, it is difficult to maintain a prescribed rotation speed. Hence, the difficulty in reading the barcode at a constant speed makes it high likely that reading errors will occur.
On the other hand, the following problem occurs when reading a barcode from a toner cartridge during insertion. That is, the barcode data cannot be stably detected since the speed at which the detachable unit is inserted varies from person to person.
A specific example of these problems will be described in accordance with FIG. 21. FIG. 21 shows the possibility of instability or reading errors occurring when reading individual information from a single label. FIG. 21 illustrates two diagrams, top and bottom.
The top diagram shows data being read correctly. Reference numeral 2105x denotes a data label, and 2300x shows the timing at which data is sampled. When there is only one label, the data sampling 2300x needs to be performed at regular time intervals. A binary signal can be read when sampling data, depending on whether the label is black or white. With the top diagram, the data can be correctly read as “110100101111001101” as in 2301x. 
On the other hand, the bottom diagram shows what happens when the rotation or insertion speed is doubled. In this case, even though the data label 2105y is the same as the data label 2105x, data can only be sampled as shown in 2300y, resulting in imported data of “110011011” as shown in 2301y. Thus, the read data is obviously incorrect.